Sovtek 6550 - Can they really be THIS bad???

Bob, it's great hearing from you! I'd really love to hear your CAT once it returns home. Knowing you, I'm sure it sounds lovely in your system.

I spent a good amount of time listening last night, and interestingly enough, the faults Albert attributed to this tube are EXACTLY what I heard. The dynamics are weak, and the sound just seems to lack the get up and go I demand. The high frequency distortion was also there in spades. Most curious was that female vocals took on a peculiar "lip smacking" effect where there should have been breathiness. Imaging was not terrible, but not up to the standard set by the JOR.

I did try the quad of JJ KT88 in one channel, and that seemed to help out a fair amount, but I was still getting the Sovtek 6550 effect masking the overall sound, so I am not 100% certain if a retube will cure things.

I went back and forth with the DA30 a couple of times, and it had a snappier, more lively, and easier to listen presentation. It's really a superlative amplifier, apart from ultimate power and not being the last word in imaging. My DA30 is one of the first integrateds Jadis ever built. I have been told by two people that later iterations modified the circuitry to enhance thermal stability of the amps, which has NEVER been in an issue with mine, at the expense of sonics. May very well be true in my experience. What it lacks in cosmetics, it sure makes up in sound.

The one combination I should have tried in retrospect was the Sovtek 6550 in the DA30. That would perhaps answer a lot of questions.

Still, this is the amp for the second system, and I'm probably putting way too much effort into the whole thing...

Joe, I might forget about this. Send me an email message in a week or two. If the amp isn't back I should at least have an ETA. Bob

Bob, will you be coming over next Saturday??? Hopefully, the answer is yes.

I did try the Sovtek 6550s in the DA30 last night, and I must say that while the amp runs out of steam before its big brother, though still within the limits of being acceptable to all but the really power thirsty, it's simply a better component sonically. Even with these tubes, while not as glorious as the JJ KT88, the sound was commendable. Despite its homely looks, whatever purity was designed into it originally, later iterations seem to have lost to some degree. Not that the DA60 is not a very good amp, it is, just that the older amp is INCREDIBLY special. The sweetness, naturalness, and even excitement is wonderful. I guess, sometimes, the old stuff really is that good.

Hi Trelja. Thanks for mentioning the possibility of the JOR being "loose" - I took this to mean that the little bolts on the casing could be loose, and sure enough tightening them virtually eradicated the hum - presumably the service guy who biased the new tubes left them a bit undone and so the casing amplified whatever resonance the transformer was creating.
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Hope your new amp works out. Regards, Rob.

Rob, I'm so happy about the JOR not having a "real" transformer issue. That would be quite painful.

You read me 100% correct in my saying "loose" meaing what you thought it meant. My idiotic ramblings are so all over the place, it's a wonder anyone can understand me sometimes. It's easy to see how a loose transformer could really buzz. The biasing of the amp should not involve loosening the transformers whatsoever, only reading a few resistors, and adjusting the respective potentiometers until the voltages on those resistors falls into spec. Still, I'm sure it could have loosened any number of ways.

Good luck with that JOR, it's one of the finest sounding amps I have ever encountered, if not the finest.